[rudymagny]

Bonjour porcinet82 et merci de ta réponse!
j'ai mis en application ta réponse et c'est pas mal du tout parce que je réduis considérablement mon module et donc plus simple pour la maintenance de mon appli:

Sub Attribuer_formule_colonnes(mois)
Sheets(mois).Activate
Columns('C:C').Select
ActiveWorkbook.Names.Add Name:='ColGet' & mois, RefersToR1C1:='=OFFSET(' & mois & '!R4C3,,,COUNTA(' & mois & '!C3)-1)'
Columns('E:E').Select
ActiveWorkbook.Names.Add Name:='ColGdP' & mois, RefersToR1C1:='=OFFSET(' & mois & '!R4C5,,,COUNTA(' & mois & '!C5)-1)'
Columns('F:F').Select
ActiveWorkbook.Names.Add Name:='ColAcc' & mois, RefersToR1C1:='=OFFSET(' & mois & '!R4C6,,,COUNTA(' & mois & '!C6)-1)'
Columns('H:H').Select
ActiveWorkbook.Names.Add Name:='ColU' & mois, RefersToR1C1:='=OFFSET(' & mois & '!R4C8,,,COUNTA(' & mois & '!C8)-1)'
Columns('O:O').Select
ActiveWorkbook.Names.Add Name:='ColCreation' & mois, RefersToR1C1:='=OFFSET(' & mois & '!R4C15,,,COUNTA(' & mois & '!C15)-1)'
Columns('P:P').Select
ActiveWorkbook.Names.Add Name:='ColRefonte' & mois, RefersToR1C1:='=OFFSET(' & mois & '!R4C16,,,COUNTA(' & mois & '!C16)-1)'
Columns('Q:Q').Select
ActiveWorkbook.Names.Add Name:='ColModifBDE1E4' & mois, RefersToR1C1:='=OFFSET(' & mois & '!R4C17,,,COUNTA(' & mois & '!C17)-1)'
Columns('R:R').Select
ActiveWorkbook.Names.Add Name:='ColModifBDE4' & mois, RefersToR1C1:='=OFFSET(' & mois & '!R4C18,,,COUNTA(' & mois & '!C18)-1)'
Columns('S:S').Select
ActiveWorkbook.Names.Add Name:='ColPanne' & mois, RefersToR1C1:='=OFFSET(' & mois & '!R4C19,,,COUNTA(' & mois & '!C19)-1)'
Columns('U:U').Select
ActiveWorkbook.Names.Add Name:='ColE1' & mois, RefersToR1C1:='=OFFSET(' & mois & '!R4C21,,,COUNTA(' & mois & '!C21)-1)'
Columns('V:V').Select
ActiveWorkbook.Names.Add Name:='ColE2' & mois, RefersToR1C1:='=OFFSET(' & mois & '!R4C22,,,COUNTA(' & mois & '!C22)-1)'
Columns('W:W').Select
ActiveWorkbook.Names.Add Name:='ColE3' & mois, RefersToR1C1:='=OFFSET(' & mois & '!R4C23,,,COUNTA(' & mois & '!C23)-1)'
Columns('X:X').Select
ActiveWorkbook.Names.Add Name:='ColE4' & mois, RefersToR1C1:='=OFFSET(' & mois & '!R4C24,,,COUNTA(' & mois & '!C24)-1)'
Columns('AB:AB').Select
ActiveWorkbook.Names.Add Name:='ColE5' & mois, RefersToR1C1:='=OFFSET(' & mois & '!R4C28,,,COUNTA(' & mois & '!C28)-1)'
Columns('AD:AD').Select
ActiveWorkbook.Names.Add Name:='ColE6' & mois, RefersToR1C1:='=OFFSET(' & mois & '!R4C30,,,COUNTA(' & mois & '!C30)-1)'
Range('A1').Select
End Sub

merci @+tard